Rotation angle detection device and rotary electric machine using same

Abstract

The rotation angle detection device includes: a magnet; a magnetic detection element disposed on the one side in the axial direction relative to the magnet with a gap interposed between the magnetic detection element and the magnet; and a shield. The shield is disposed at a location in the axial direction between a location in the axial direction of a wire member allowing current to flow therethrough and a location in the axial direction of the magnetic detection element, is disposed radially outward of the magnet as seen in the axial direction, and has a portion that overlaps with the wire member as seen in the axial direction. The wire member is disposed at a location in the axial direction that is closer to the magnet than the magnetic detection element is, and is disposed radially outward of the magnet as seen in the axial direction.

What is claimed is: 
     
         1 . A rotation angle detection device comprising:
 a magnet provided on one side in an axial direction of a shaft and configured to rotate integrally with the shaft;   a magnetic detection element disposed on the one side in the axial direction relative to the magnet with a gap interposed between the magnetic detection element and the magnet; and   a shield formed from a magnetic material, wherein the shield
 is disposed at a location in the axial direction between a location in the axial direction of a wire member allowing current to flow therethrough and a location in the axial direction of the magnetic detection element, 
 is disposed radially outward of the magnet as seen in the axial direction, and 
 has a portion that overlaps with the wire member as seen in the axial direction, and 
   the wire member is
 disposed at a location in the axial direction that is closer to the magnet than the magnetic detection element is, and 
 disposed radially outward of the magnet as seen in the axial direction. 
   
     
     
         2 . The rotation angle detection device according to  claim 1 , wherein
 the wire member has a circumferentially-extending portion extending in a circumferential direction, and   the shield has a portion extending in the circumferential direction so as to overlap with the circumferentially-extending portion as seen in the axial direction.   
     
     
         3 . The rotation angle detection device according to  claim 2 , wherein
 the wire member is formed in a shape of a sheet curved on a same plane perpendicular to the axial direction, a surface of the sheet being perpendicular to the axial direction, and   the shield is formed in a shape of a sheet curved on a same plane perpendicular to the axial direction, a surface of the sheet being perpendicular to the axial direction.   
     
     
         4 . The rotation angle detection device according to  claim 1 , further comprising
 an additional shield disposed on the one side in the axial direction relative to the magnetic detection element with a gap interposed between the additional shield and the magnetic detection element, wherein   the shaft is formed from a magnetic material through which a magnetic flux passes in the axial direction, and   a magnetic detection direction of the magnetic detection element is perpendicular to the axial direction.   
     
     
         5 . The rotation angle detection device according to  claim 4 , wherein
 the additional shield is formed in a shape of a sheet, and   the additional shield is disposed such that a surface of the sheet thereof is perpendicular to the axial direction.   
     
     
         6 . The rotation angle detection device according to  claim 1 , wherein the shield is disposed at a location in the axial direction between a location in the axial direction of the magnet and the location in the axial direction of the magnetic detection element. 
     
     
         7 . The rotation angle detection device according to  claim 1 , wherein a distance in the axial direction between the location in the axial direction of the shield and the location in the axial direction of the magnetic detection element is shorter than a distance in the axial direction between the location in the axial direction of the shield and the location in the axial direction of the wire member. 
     
     
         8 . The rotation angle detection device according to  claim 1 , wherein a width in the axial direction of the shield is smaller than a width in a radial direction of the shield. 
     
     
         9 . The rotation angle detection device according to  claim 1 , wherein
 a shape of the shield is similar to a shape of the wire member around the shaft as seen in the axial direction, and   the shield and the wire member overlap with each other as seen in the axial direction.   
     
     
         10 . The rotation angle detection device according to  claim 1 , wherein the shield has an annular shape extending in a circumferential direction. 
     
     
         11 . The rotation angle detection device according to  claim 1 , wherein an end portion on a radially inner side of the shield is bent toward another side in the axial direction. 
     
     
         12 . The rotation angle detection device according to  claim 1 , wherein
 the magnet has N (representing an even number that is two or more) magnetic poles on the one side in the axial direction and has N magnetic poles on another side in the axial direction,   the N magnetic poles on the one side in the axial direction and the N magnetic poles on the other side in the axial direction are disposed at locations that coincide with each other in a circumferential direction,   two of the magnetic poles that are adjacent in the axial direction are different from each other, and   two of the magnetic poles that are adjacent in the circumferential direction are different from each other.   
     
     
         13 . The rotation angle detection device according to  claim 12 , further comprising
 a holder fixed to an end portion on the one side in the axial direction of the shaft and holding the magnet, wherein   the holder has a circumferential wall covering a radially outer side of the magnet and formed from a magnetic material.   
     
     
         14 . The rotation angle detection device according to  claim 1 , wherein the magnetic detection element is a magnetoresistive effect element having a magnetic detection direction perpendicular to the axial direction. 
     
     
         15 . The rotation angle detection device according to  claim 1 , further comprising
 a support member fixing another side in the axial direction of the shield and the one side in the axial direction of the wire member to each other, wherein   the support member is formed from an insulation material, and   the shield and the wire member are electrically insulated from each other.   
     
     
         16 . The rotation angle detection device according to  claim 15 , wherein the shield has a cut into which a fitting portion provided to the support member is fitted. 
     
     
         17 . The rotation angle detection device according to  claim 15 , wherein
 the shield has a through hole penetrating therethrough in the axial direction, and   the support member is provided at: a portion within the through hole; and a portion on the one side in the axial direction of the through hole and the shield around the through hole.   
     
     
         18 . The rotation angle detection device according to  claim 1 , further comprising
 a holder fixed to an end portion on the one side in the axial direction of the shaft and holding the magnet, wherein   the holder has a tubular circumferential wall covering a radially outer side of the magnet with a gap interposed therebetween, and   the gap between the radially outer side of the magnet and the circumferential wall is filled with a fixation member.   
     
     
         19 . A rotary electric machine comprising:
 the rotation angle detection device according to  claim 1 ;   the shaft;   the wire member;   a rotor configured to rotate integrally with the shaft and having a field winding and a field core around which the field winding is wound;   a stator disposed radially outward of the rotor and having a stator core around which an armature winding is wound; and   a bracket covering an outer side of each of the rotor and the stator and holding one end side and another end side of the shaft via bearings.